1. Field of the Invention
The present invention relates to a wafer formed with a CSP device and a test socket of a BGA device in which a test socket has a contact member to perform a wiping action for increasing an electric conductivity between a wafer formed with a CSP device and a solder ball formed at a BGA device and a test socket.
2. Description of the Prior Art
In general, a BGA device formed like a ball grid array(BGA) type reacts with an air thereby to easily form a natural oxide layer when being tested at a high temperature. The natural oxide layer causes an electrical connection between a solder ball and a test device to be deteriorated when the BGA device is tested. Accordingly, the BGA device can not be correctly tested by the test device. Accordingly, a wiping action is required to remove the natural oxide layer on the solder ball.
The conventional test socket of the BGA device for performing the wiping action will now be described with reference to FIG. 1.
FIG. 1 is a sectional view showing a conventional test socket of a BGA device.
FIG. 1 shows a state that the BGA device 1 arranged with the solder ball 1a by a predetermined distance is contacted with a load board 4 by the test socket. A contact member 3 of the test socket is installed at a housing in two-dimension and is at its one end contacted with the solder ball 1a of the BGA device and is at its other end contacted with the load board 4. Under this state, a test signal is transmitted to the BGA device through the load board 4 to be performed the test.
Under the test signal being transmitted to the BGA device 1 the contact member 3 is occurred with a parasitic inductance and a capacitance when being operated at a high frequency region above hundreds of MHz and when the contact member is long. Accordingly, to minimize the phenomenon like that, the contact member 3 should be formed to have S-shape thereby to be shorten its distance. The contact member 3 having S-shape is its one end 3a contacted with the surface of the solder ball 1a, and, at this time, a wiping action is performed to remove the natural oxide layer on the solder ball 1a. 
For the wiping action a housing 2 for fixing the contact member 3 should be formed by an elastic material of non-conductivity. The contact member 3 contacted to the housing 2 bends its one end 3a by a pressing force of the BGA device 1 thereby to perform a movement as a fixing member.
By the elastic force owing to the movement like that the contact member 3 pushes the solder ball 1a by an appropriate force to perform the wiping action. Next, the contact member 3 is returned to its original state when the BGA device 1 is deviated.
The contact member 3 is, as shown in FIG. 1, disposed inside of the housing 2. The contact member 3 being assembled to the housing 2 is manufactured one by one and assembled to the housing 2 thereby causing the manufacturing time of the contact member 3 and the process for assembling to the housing 2 to be increased. Accordingly, a manufacturing time for the test socket is increased.
Furthermore, the modularized contact member 3 forces the solder ball 1a of the BGA device 1 not to be correctly arranged when a vibration is occurred by the contact force. Because the solder ball 1a is at its one side pressed by a pressing force when the contact member 3 performs the wiping action by its one end, the solder ball 1a being contacted to the BGA device 1 is deformed or separated.
That is, because the BGA device 1 become weaken its mechanical strength owing to the low fusion point of the solder ball 1a during a test by a high temperature, the solder ball 1a is received with a non-symmetrical force thereby causing the solder ball 1a of the BGA device 1 to be deformed.
Accordingly, the present invention has been invented to solve the above problems, it is an object to provide a test socket of a BGA device in which a contact member block formed integrally with two-dimensionally arranged contact member is provided to apply an uniform force to a solder ball of a BGA device when a wiping action is performed.
Another object of the present invention is to provide a test socket of a BGA device in which a contact member is contacted with the surface of a solder ball by an uniform force in order to prevent a deformation or a separation of the solder ball when a wiping action is performed to remove a natural oxide layer.
Other object of the present invention is to provide a test socket in which a contact member is modularized to apply an uniform force to a solder ball in order for a wafer formed with a CSP device to be connected to a test device when the solder ball on the wafer formed with the CSP device and the test device are electrically connected.
To achieve the above objects the present invention provides a test socket comprising: a contact member block having a slanting face to apply an uniform pressing force to the surface of a solder ball when a BGA device is contacted with the solder ball, formed with a two-dimensionally arranged long hole, the long hole being formed at its central portion with a through hole, the slanting face of the long hole and the surface of the through hole being coated with a conductive material; and a housing formed with a contact member block groove for mounting the contact member block and formed at the upper portion of the groove with a mounting portion for receiving a BGA device.
Furthermore, the present invention provides a test socket comprising: a housing formed with a mounting portion for a BGA device and formed inside of the mounting portion with a plurality of two-dimensionally arranged contact member through hole; and a plurality of contact members formed with a coupling portion for being inserted with the through hole, formed at the upper portion of the coupling portion with a square pillar, wherein the square pillar being formed with a long hole having a slanting face to apply an uniform pressing force to the surface of the BGA device when the BGA device is contacted with the solder ball, the slanting face and the surface of the through hole being coated with a conductive material.
The present invention provides a test socket comprising: a wafer housing including a mounting portion for mounting a wafer and two-dimensionally arranged contact member module groove; a contact member module coupled to the groove corresponding to a solder ball of a CSP device on the wafer.